-415 The corresponding columns in each table of a UNION do not have the compatible data types.

Explanation
The corresponding columns in each table of a UNION must
have compatible data types based on the position of each column in the UNION
select list. For example, the first item in each select list in a UNION must
be compatible with the first item in every table in the UNION. 

User response
Correct the SQL statement. If the incompatible column
is not apparent by sight-checking the SQL, consult the data server log for
more information on the column that resulted in this error.